I haven't registered as a member, but I get an email from whooing

I haven't registered as a member, but I get an email from whooing

Users can use various types of household account book apps on Android/iPhone apps through whooing's [third party] (/help/tips/thirdparty) policy. Whooing is a form in which only data is provided and the usage environment is controlled by a third party created by each developer. If you encounter whooing using such a third party, you can sign up for whooing without knowing the service called whooing (though of course you go through the membership registration process).